Anti-quorum sensing and antimicrobial activity of aromatic species from South America

Abstract

Quorum sensing (QS) is a bacterial communication mechanism that depends on population density. The interruption of QS is one example of an antipathogenic effect. We investigated the anti-QS and antimicrobial properties of essential oils from Argentina: Salvia officinalis, Minthostachys mollis, Satureja odora, Schinus molle, Lepechinia floribunda and Artemisia annua. Anti-QS activity was determined by measuring the production of violacein in Chromobacterium violaceum through UV–visible spectrophotometry and the minimal QS inhibitory concentration (MQSIC) was calculated. The antimicrobial activity was determined using Escherichia coli, Listeria innocua and Staphylococcus aureus as indicators. Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were determined by performing the broth microdilution assay. Minthostachys mollis showed statistically significant QS inhibition properties. This essential oil reduced pigment production by 90% when it was applied at a sublethal concentration (0.02% v/v). Conversely, the highest bacteriostatic and bactericidal activity was exhibited by S. molle oil. Minthostachys mollis essential oil is a good candidate for the development of anti-QS products with a potential application in the control of bacterial diseases mediated by QS. As this strategy interferes with the expression of pathogenic traits rather than killing the microorganism or impeding microbial growth, it avoids the problem of resistance.

Keywords:

• Chromobacterium violaceum
• Escherichia coli
• Listeria innocua
• Staphylococcus aureus
• essential oils
• quorum sensing

Acknowledgements

This research was supported by Comisión de Investigaciones Científicas (CIC), Buenos Aires and a PICT 2008-1624 FONCyT grant to Sandra R. Fuselli.